Fluid Flow problems
- 1. A pseudoplastic fluid is one in which the viscosity
Options- A. is constant regardless of the stirrer speed or mixing time
- B. changes during mixing but returns to its original state after mixing
- C. increases with increasing stirrer speed
- D. decreases with increasing stirrer speed Discuss
Correct Answer: decreases with increasing stirrer speed
- 2. The medium will have the highest viscosity (considering that the cells do not secrete gums) with the presence of
Options- A. single celled bacteria
- B. filamentous fungi that form pellets
- C. filamentous fungi that grow as long poorly branched chains
- D. yeast Discuss
Correct Answer: filamentous fungi that grow as long poorly branched chains
- 3. The viscosity of a fluid changes with either stirrer speed or mixing time. But when mixing ceases, the viscosity returns to its original state. This fluid is best described as
Options- A. newtonian
- B. rheopectic
- C. viscoelastic
- D. thixotropic Discuss
Correct Answer: viscoelastic
- 4. A liquid is flowing at 11,400 l.h-1 along a pipeline having a diameter of 4 cm. If the liquid has a density of 1 g.ml-1 and viscosity of 0.001kg.m-1.s-1, then the liquid would be in the
Options- A. laminar phase
- B. transient phase
- C. turbulent phase
- D. any of the phase Discuss
Correct Answer: turbulent phase
- 5. Bubble free aeration systems requires
Options- A. silicone tubing or gas permeable membranes to facilitate gas transfer
- B. carbon dioxide instead of air to supply oxygen
- C. silicone tubing or gas permeable membranes to remove carbon dioxide by oxygen in the form of hydrogen peroxide
- D. filled headspace of the reactor with carbon dioxide Discuss
Correct Answer: silicone tubing or gas permeable membranes to facilitate gas transfer
- 6. If the viscosity of a fluid decreases with the length of time that it is being mixed, then this fluid is
Options- A. newtonian
- B. rheopectic
- C. viscoelastic
- D. thixotropic Discuss
Correct Answer: thixotropic
- 7. A viscoelastic fluid is one in which the viscosity
Options- A. is constant regardless of the stirrer speed or mixing time
- B. changes during mixing but returns to its original state after mixing
- C. increases with increasing stirrer speed
- D. decreases with increasing stirrer speed Discuss
Correct Answer: changes during mixing but returns to its original state after mixing
- 8. Which of the following is correct?
Options- A. The viscosity of liquids and gases decrease with increasing temperature
- B. The viscosity of liquids and gases increase with increasing temperature
- C. the viscosity of gases increases with increasing temperature, but decreases in liquids
- D. the viscosity of gases decreases with increasing temperature, but decreases in liquids. Discuss
Correct Answer: the viscosity of gases increases with increasing temperature, but decreases in liquids
- 9. Pluronic F68 protects mammalian cells from damage stems as it is a/an
Options- A. surface active agent which stabilizes foams
- B. surface active agent which destabilizes foams
- C. excellent source of vitamins
- D. coagulant Discuss
Correct Answer: surface active agent which stabilizes foams
- 10. Mixing in stirred tank reactors can
Options- A. be described as either laminar, transient or turbulent
- B. achieve turbulent conditions by increasing the stirrer speed
- C. induce laminar flow conditions by the addition of baffles
- D. all of the above Discuss
Correct Answer: be described as either laminar, transient or turbulent
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